Active Surveillance of Differentiated Thyroid Cancer Metastatic Cervical Lymph Nodes: A Retrospective Single-Center Cohort Study

Background: The most frequent site of recurrence of differentiated thyroid cancer (DTC) is cervical lymph nodes (LNs), which often necessitates repeated surgical interventions and morbidity in a generally indolent disease. Data on active surveillance (AS) of small cervical nodal metastasis are still scarce, particularly in real-world clinical settings. In this study, we evaluated the DTC outcomes of AS of metastatic cervical LNs and explored factors associated with disease progression. Methods: We conducted a retrospective cohort study, including DTC patients with biopsy-proven metastatic cervical LNs, who were followed on AS in a tertiary care, university-based institution in Brazil. The inclusion criteria were cervical metastasis ≤2.0 cm and an AS duration of at least 6 months. We excluded lesions with aggressive histology, those in close proximity to or invading local structures. The primary outcome was disease progression (enlargement ≥3 mm in any diameter or a new cervical metastasis). Results: Data from 40 patients were analyzed. Most were female (77.5%) and had papillary thyroid cancer (97.5%). The mean age was 47.0 (± standard deviation 15.8) years. The 8th edition of the tumor, node, metastasis stage (TNM8) staging for DTC was as follows: 29 in stage I (74.4%), 8 in stage II (20.5%), and 2 in stage IV (5.0%). The median maximum LN diameter was 0.9 (interquartile range IQR, 0.8-1.3) cm, and the median AS follow-up duration was 27.5 (IQR, 16.5-47.3) months. Disease progression occurred in 14 (35%) patients: 7 (17.5%) due to enlargement ≥3 mm, and 7 (17.5%) had new cervical metastasis. The cervical progression-free survival was 51.0 (confidence interval, 47.0-55.0) months. No demographic, oncological, or biochemical factors were associated with disease progression. Of the 14 patients with disease progression, 8 were referred for surgery. No permanent surgical complications were reported. Of the six patients who remained on AS despite disease progression, five showed no further progression during subsequent follow-up (range 6-40 months). Conclusions: We observed that most small metastatic cervical LNs remained stable and were safely managed with AS. Nevertheless, these observations are limited by the retrospective design, small sample size, and short follow-up. Further prospective and long-term studies are warranted.